1. Field of the Invention
The present invention relates generally to the construction and use of medical catheters. More particularly, the invention relates to an intravascular catheter system having a plurality of interchangeable components which allow a treating physician to modify the catheter assembly based on the condition of a particular patient.
Arteriosclerosis, also known as atherosclerosis, is a common human ailment arising from the deposition of fatty-like substances, referred to as atheroma or plaque, on the walls of blood vessels. Such deposits occur both in peripheral blood vessels that feed the limbs of the body and coronary blood vessels which feed the heart. When deposits accumulate in localized regions of a blood vessel, blood flow is restricted and the person's health is at serious risk.
Numerous approaches for reducing and removing such vascular deposits have been proposed, including balloon angioplasty where a balloon-tipped catheter is used to dilate a region of atheroma, atherectomy where a blade or other cutting element is used to sever and remove the atheroma, and laser angioplasty where laser energy is used to ablate at least a portion of the atheroma. In addition to such therapeutic approaches, a variety of techniques for transluminal imaging of atheroma and other diseased regions of the blood vessel have been proposed, including endoscopic imaging techniques and ultrasonic imaging techniques.
Even after a particular interventional approach has been selected, a particular catheter design incorporating the necessary therapeutic and/or diagnostic features must be chosen. Differences in patient anatomy, the location of the atheroma, the nature of the atheroma (particularly the degree of calcification), physician technique, and the like, can all dictate different configurations of the catheter.
For example, all types of vascular catheters generally employ a guide assembly which allows the physician to advance the catheter through the desired blood vessels. Such guide assemblies can comprise fixed guide wires or movable guide wires, where the movable guide wires may be received by central lumens (in an "over the wire" configuration) or an offset lumen (in a "monorail" configuration). For particular applications, each type of guide assembly may be further matched with one, two, three, or more, additional features, resulting in a very large number of potential configurations.
In the case of atherectomy catheters, choices exist between the type of cutting element employed, the type of collection chamber utilized for retaining the severed atheroma, as well as additional specific features which may be desirable for particular therapeutic techniques. A similar array of specific features exists for each of the laser, balloon, and imaging catheter systems.
In order to afford the necessary selection of features, physicians and hospitals have heretofore had to maintain very large inventories of catheters to provide the various combinations which a patient might require. It has been necessary to maintain the inventory at the hospital since the conditions observed during a therapeutic procedure may indicate the use of a different catheter. Maintenance of such large inventories of catheters can be very expensive, and it may in fact be impossible to maintain as large an inventory as would be desirable. In the latter case, a physician might have to compromise the selection of catheter when confronted with a condition which was unknown at the outset of the procedure.
It would therefore be desirable to provide catheter systems which can be configured to include a variety of specific features and capabilities and which allow the treating physician to modify the catheter construction as needed at the outset and during the course of a therapeutic and/or diagnostic procedure. Such a catheter system would both reduce the inventory of catheters which must be maintained by the physician or the hospital and would enhance the availability of catheters tailored to meet specific therapeutic and imaging needs. It would be particularly desirable to provide atherectomy catheter systems having the capability of selecting among different types of guide assemblies, collection chambers, cutting elements, and other features as described in more detail hereinafter.
2. Description of the Background Art
European Patent Application 163 502 and U.S. Pat. No. 4,669,469, the disclosures of which are incorporated herein by reference, each describe an atherectomy catheter comprising a distal housing having an axially translatable blade therein. The blade may be moved past a side opening in the housing to sever adjacent atheroma in a blood vessel. Copending application Ser. No. 07/312,108, now U.S. Pat. No. 5,047,040 the disclosure of which is incorporated herein by reference, describes an atherectomy catheter comprising a distal housing or collection chamber having an axially translatable blade, where the blade may be extended forwardly of the housing to sever atheroma. The housing is illustrated to be screwed onto a fitting on the catheter tube, but no suggestion is made that different housings may be substituted. Copending applications having Ser. Nos. 07/045,916abandoned; 07/117,072abandoned ; and 07/298,846now U.S. Pat. No. 4,979,951 , each of which is incorporated herein by reference, describe atherectomy catheters having non-interchangeable functional components corresponding generally to certain of the interchangeable functional components of the present invention. U.S. Pat. No. 4,494,549, discloses a combined optical and ultrasonic endoscope having a detachable ultrasonic scanner which may be replaced by a cover 33.